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Our achievements:
Diffusion of probes rotating in the RPM took approximately twice as long compared to static controls. This proves the RPM's ability to reduce diffusion rates by simulating microgravity conditions.
Goal: The aim of this project was to create a validated, open-source Random Positioning Machine (RPM) that allows researchers and students to simulate microgravity and partial gravity in a laboratory setting. Commercial RPMs are prohibitively expensive, preventing many groups from investigating how biology behaves in space-like environments.
We designed and validated a low-cost, open-source Random Positioning Machine as a microgravity simulator for just 150-180 €. Unlike existing DIY projects, our RPM has an operating system and was experimentally verified using a mobile phone IMU (LSM6DSOX). At a feed rate of 50 mm/min the averaged effective gravity reached 0.028-0.070 g (see Table 1), confirming simulated microgravity. By adjusting the feed rate, any gravitational acceleration could be simulated at the cost of more centrifugal force.
Create a validated, open-source RPM for simulating microgravity/partial gravity.
Feed-rate control + IMU validation; dye diffusion test inspired by NASA’s protocol.
Effective gravity down to 0.028-0.070 g at 50 mm/min; ~2× slower diffusion under rotation.
| F: Feed rate [mm/min] | Average effective gravity (× g) |
|---|---|
| 400 | 0.73 |
| 300 | 0.52 |
| 200 | 0.28 |
| 100 | 0.09 |
| 50 | 0.053 |
To validate the RPM’s ability to simulate microgravity, we developed and optimized a simple dye diffusion test inspired by NASA’s protocol [1]. Using this method, we demonstrated that the rotating sample required roughly twice as long to fully diffuse as the static control, clearly showing that the RPM effectively reduces diffusion and mimics microgravity conditions.
Inspired by NASA’s dye diffusion test [1], we optimized and changed the protocol to observe the dye diffusion easily at home. With 0.5 % agar and 50 ml Falcon tubes it was possible to distinguish between a static and rotating sample (see Figure 1). After 20 minutes, the dye in the static tube had already started to spread evenly, while it remained concentrated at the center in the RPM tube. After 50 minutes, the static tube was fully diffused, whereas the RPM tube still displayed a distinct undyed region. Only after 100 minutes did the RPM tube appear uniformly colored. In blind evaluations, a handful of team members were consistently able to recognize the RPM samples, confirming the robustness of the effect. The final protocol is inexpensive, easy to replicate, and can even be reproduced at home using food coloring and a pipette.
The RPM can be used for future in vivo research studies, particularly in combination with our water purification system. For example, it allows controlled studies of plant growth with purified water under Martian gravity on Earth.
We set out to make the complex, oxygen-sensitive enzyme perchlorate reductase (PcrAB) accessible for iGEM-level expression and characterization. Through four engineering cycles we designed, built, and tested expression constructs and began rational enzyme engineering to improve activity. Below we summarize key experimental outcomes, their significance, and next steps.
We aimed to express active PcrAB with a Strep-Tag II for straightforward purification. We successfully cloned a pcrABD operon lacking pcrC into an IPTG-inducible expression system and expressed it in E. coli BL21(DE3). Slow growth under anaerobic conditions was observed, but lysates showed perchlorate-reducing activity (see Figure 2). Using phenazine-methosulfate (PMS) and NADH, we measured NADH oxidation corresponding to perchlorate reduction at 340 nm in cuvettes overlaid with mineral oil [2]. Lysate from cultures induced with 100 µM IPTG showed the highest activity, giving a linear NADH consumption rate of ~2.7 nM min⁻¹, while GFP expressing negative controls showed no activity (see Figure 2,3). Compared to cultures induced with lower concentrations, such as 50 µM, this condition yielded the strongest activity, as depicted in Figure 3.
Next we sought to easily purify PcrAB by utilizing its Strep-Tag II for affinity chromatography. Purification yielded two bands on the SDS-PAGE for the wash fraction, suggesting the enzyme bound too weakly to the resin (see Figure 4). Nevertheless, thereby obtained PcrAB seems to be pure. PcrA exhibits mass of 104 kDa and PcrB 37 kDa [3].
Plasmids carrying verified pcrA Y165H and W461H mutations were transformed into E. coli BL21(DE3) for small-scale expression under the same anaerobic and induction conditions as our wild-type pcrABD construct. Lysates were evaluated by the PMS/NADH assay to compare NADH consumption rates, see Figure 5.
Assays of the Y165H and W461H mutations showed no detectable perchlorate degradation compared to the Tris-HCl buffer control, indicating that the enzyme was not functional. These histidine substitutions likely disrupted the critical aromatic “gate” residues of PcrA, impairing substrate binding and electron transfer [3]. Alternatively, oxygen sensitivity of the employed assay obscured activity.
Our work demonstrates, for the first time, functional expression of active, affinity-tagged perchlorate reductase in E. coli and establishes an assay platform for its characterization. These advances lower the technical barrier for studying and engineering this key enzyme, moving iGEM and the broader scientific community closer to deployable microbial solutions for perchlorate detoxification on Earth and Mars.
Chlorite dismutase (Cld) catalyzes the rapid detoxification of chlorite into chloride and oxygen, see Figure 6 [4]. This is the second step of biological perchlorate reduction [5].
As Cld is critical to break down toxic chlorite to prevent it from harming our chassis [5], we decided to purify and characterize Azospira oryzae GR-1 Cld extensively in vitro and derive implications for its implementation in Bacillus subtilis. We were able to successfully purify it via IMAC and investigate an alternative, low-cost and fast activity assay. Details about methodology can be read at the iGEM part registry.
Cld was produced in E. coli BL21(DE3) pLysS and purified using a HisTrap column (Cytiva) (read details). The process was analyzed on an SDS-PAGE (Figure 7). Overproduction upon induction as well as binding and elution from the HisTrap column were verified. Cld stock is very pure, with only slight contamination by a ~60 kDa protein.
Protein (monomer) concentration was determined to (63 ± 7) µM via Bradford Assay [6]. Yield was probably reduced due to poor elution from the column, in contrast to descriptions in the literature [7]. Nevertheless, obtained Cld stock was completely sufficient, as only nM concentrations are needed for activity assays.
To quantify heme b amount in Cld stock solution, the pyridine hemochrome assay was employed. This assay exploits the fact that pyridine forms complexes with heme groups, which show distinct absorption spectra upon reduction to the ferrous state by sodium dithionite. From absorption at peak subsequently heme concentrations can be calculated using the extinction coefficient ε556nm=34.7 mM-1cm-1 [8]. This assay was used to verify if every Cld monomer is bound to a prosthetic heme-group, as in that case Cld and heme concentrations should be equal. Any free heme should have been removed during the two chromatographic steps during purification. In Figure 8 absorption spectra of oxidized and reduced heme from purified Cld are shown.
Heme concentration could be determined to 68 µM. This value is within error range of (63±7) µM Cld protein concentration. Thus heme and Cld concentrations can be considered equal within (substantial) measurement inaccuracies and so every Cld subunit should have a prosthetic heme-group bound. Because tight heme binding is only possible with a correctly folded ferredoxin-like binding pocket [5], every Cld molecule should be correctly folded and active.
Degradation of chlorite into chloride and oxygen was monitored spectroscopically at 260 nm
[9,
10]. This method allows fast and easy measurement of chlorite concentrations.
As neither of the products absorbs light at 260 nm, direct evaluation of leftover chlorite concentration is possible
[11].
Because chlorite degradation by Cld is very fast, it is critical to start the measurement immediately after adding Cld to chlorite solution. To ensure efficient mixing nevertheless, always 200 µl Cld solution was pipetted to 200 µl chlorite solution. Control experiments with 200 µl heat-inactivated Cld show stable absorbance, see Figure 9a, indicating both solutions get thoroughly mixed through flux caused by pipetting. Otherwise, diffusion of chlorite/buffer into the light path should have caused fluctuations in absorbance.
By applying this procedure, kinetics could be evaluated on a Nanocolor UV/Vis II spectrometer designed for completely different applications (water/waste-water analysis). As most labs have access to standard photometers, we hope this assay is accessible to many iGEM teams.
Our results show that Cld gets inactivated after a certain amount of turnovers and thus does not decompose chlorite completely. Cooler reaction temperatures lead to higher turnover numbers.
As can be seen in Figure 9a, at room temperature absorption stabilizes around 0.11, indicating not all chlorite gets degraded. This is because hypochlorite is produced as intermediate during chlorite degradation, and it probably reacts with the heme-group or tyrosine residues leading to irreversible Cld inactivation [10]. Plotting the chlorite turnover number within 1 min against initial chlorite concentration reveals enzyme inactivation after conversion of ~0.3 µmol chlorite per unit of Cld (Figure 9b), similar to previously reported data (0.38 µmol/U for Cld from Dechloromonas agitata CKB [4]).
Comparison of total chlorite conversion at room temperature and when mixing ice-cold substrate and Cld solutions together showed significantly more chlorite converted for the latter (p<0.1% for Figure 9a after 1 min), see Figure 9. This temperature influence on Cld inactivation is known [11] and might be explained by the fact that transiently produced hypochlorite needs to escape the active site in order to inactivate Cld [10]. As lower temperature slows down diffusion, this escape might become less likely.
Despite changing total chlorite conversion, reaction temperature did not cause significant activity changes. For Figure 9a initial velocities were (11.6±1.5) µM/s and (10.2±1.4) µM/s for ice-cold and room temperature reactions respectively (p>24%).
Thus, lower reaction temperature can be used to improve activity assay accuracy, by increasing initial linear phase of reaction.
During some recorded kinetics, poor linearities in Lineweaver-Burk-Plots were obtained. This could be attributed to the fact that Cld activity decays when stored on ice for a measurement relevant time scale. Activity only decays in low concentrated solutions.
In Figure 10 activity remaining after storing different Cld solutions on ice is displayed. Complementary to activity, also total chlorite conversion was used to evaluate decrease of active Cld.
Storing 6.3 nM Cld solution (typical assay concentration) for 100 min on ice leads to ~30% activity/chlorite conversion loss (p<5%). This substantially tampers kinetic measurement series. In contrast, both 630 nM Cld solution as well as 6.3 nM Cld with 0.001% Triton X-100 did not exhibit significant activity/chlorite conversion loss (all p>10%).
The observed decay of active enzyme is surprising, as pentameric Cld is known for its thermostability [12]. The instability of less concentrated Cld solutions could be due to a shift in the oligomerization equilibrium toward monomeric Cld. Monomeric Cld is expected to be less stable than pentameric due to exposed hydrophobic surfaces which are covered in pentameric form.
Triton X-100 could accordingly stabilize pentameric or monomeric Cld, as it stabilizes other enzymes by masking exposed hydrophobic surfaces [13]. Thus, Triton might be suited to stabilize low-concentrated Cld in order to perform accurate assays. However, further experiments would need to verify that activity really does not decay in presence of Triton first, as measurements shown here exhibit high standard deviations which might obscure significant activity loss.
| Parameter | Linear fit | Exponential fit | Literature |
|---|---|---|---|
| kcat [1/s] | 2800 ± 410 | 4910 ± 750 | 1170 |
| KM [µM] | 178 ± 26 | 377 ± 47 | 170 |
Both Lineweaver-Burk plots exhibit good linearity, see Figure 11b. This is in contrast to measurements where
Cld solution was not freshly prepared each time (see our
engineering page). When applying linear regression,
the determined KM constant matches the previously reported value. However, kcat is more than twice
as high as expected
[14]. That this is caused by actually higher Cld stock concentration than determined seems unlikely,
as it would contradict both Bradford as well as pyridine hemochrome assay results.
In contrast, the deviation could be caused by varying reaction conditions between this experiment and literature.
Both in our experiments as well as previous reports reaction temperature did not influence initial degradation rates.
Also, differences in phosphate buffer concentrations should not alter activity
[11]. Potentially different expression
and purification methods or spontaneous activity decay, as described earlier, led to lower determined kcat in
[14].
As can be seen in Figure 11a, exponential regression fits the degradation curve better than linear regression.
Also, initial velocity variance within triplicates shrinks and linearity of the Lineweaver-Burk plot increases
(Figure 11b).
As expected, thereby determined kcat is greater. However, obtained kinetic values cannot be verified as - to
our knowledge - Cld from Azospira oryzae GR-1 was only analyzed using linear regression so far
[14].
Nevertheless, applying exponential regression seems more accurate to fit obtained degradation curves. Also, similar
substrate dependence of chlorite degradation and enzyme inactivation rates were reported, which implies inactivation
after a fixed number of turnovers. Thus, in reality the degradation curve should be closely represented by an exponential
function
[4].
To investigate oligomeric state of Cld it was subjected to Taylor/non-Taylor native mass spectrometry (TNT-MS) [15]. Using this method, it was possible to verify that Cld forms homopentamers in solution and our purified Cld has full heme-occupancy. Interestingly, a homodemameric Cld species was also observed
In native MS, proteins are ionized by electrospray ionization (ESI) preserving non-covalent interactions such as protein complexes. Subsequently mass-over-charge ratio (m/z) of these ions is determined, in our case by evaluating their flight time in vacuum. By analyzing two neighboring charge states of one molecular species, its mass can be derived. (If x1=m/z and x2=m/(z+1), charge state can be calculated by z=x2/(x1−x2). Subsequently mass can be derived using m=x1·z.) From that, oligomeric state as well as e.g. bound ligands can be identified, as the masses of both ligand and monomeric apo-protein are known [16].
Here TNT-MS was used to rapidly buffer-exchange Cld into MS-compatible ammonium acetate buffer. For this the protein sample was injected into ammonium acetate buffer flowing through a capillary. Because of their higher hydrodynamic radius, part of the protein sample traverses the capillary faster than small molecules and is thus buffer-exchanged to enable subsequent MS analysis [15].
To gain more information, precursor ions can be subjected to collision-induced dissociation (CID) before m/z measurement. For this, the precursor ions are accelerated into neutral gas. Regarding protein complexes this usually yields asymmetric charge partitioning, meaning dissociation of a highly charged monomer from the complex [17]. Here collision with neutral gas was used to mildly activate precursor ions, thereby stripping off unspecific adducts and thus increasing accuracy and resolution.
Cld forms homopentamers in solution [18]. Therefore, signals corresponding to ions with mass of five Cld subunits and five heme-groups are expected. In addition, CID should result in ejection of monomers and heme-groups. Mass spectra are shown in Figure 12, calculated masses are displayed in Table 3.
| Parameter | apo-monomer | holo-monomer | Pentamer | Decamer |
|---|---|---|---|---|
| Theoretical mass [Da] | 29 757.0 | 30 371.5 | 151 857.7 | 303 715.4 |
| Average observed mass [Da] | 29 755.9 | 30 373.1 | 152 204.8 | 304 848.3 |
| Standard deviation [Da] | 0.9 | 3.3 | 92.0 | 119.0 |
| Mass error relative to theoretical [ppm] | 37 | 52 | 2286 | 3730 |
Chlorite dismutase is of critical interest for (per)chlorate and chlorite bioremediation as it catalyzes the rapid detoxification of chlorite into harmless chloride and oxygen
[4]. In addition, it can be exploited to create oxygen for different applications
[19, 20], which might also prove useful for future space missions
[21].
Here we show first successful Cld production and purification by an iGEM team. We investigated and optimized a spectroscopic activity assay that was performed on a Nanocolor UV/Vis II photometer, designed for completely different applications. It is faster and easier to perform compared to discontinuous methods like iodometric titration
[4]. As many labs already have a photometer capable to measure kinetics, this method is hopefully accessible to many iGEM teams eradicating the need to invest into highly expensive Clark-oxygen sensing electrodes.
Using this assay, it was possible to evaluate Cld kinetics as well as turnover numbers. However, it is not as accurate as alternative methods due to poor time and chlorite concentration resolution.
In addition, it could be verified that AoCld forms homopentamers in solution by native MS. Interestingly, a decameric form also seems to be present. Further research into its abundance and potential biological role seem highly interesting.
Research into Cld verified its successful heterologous expression and rapid chlorite degradation
[4], crucial because of chlorite’s cytotoxicity
[22]. These results indicate Cld could work to ensure efficient perchlorate degradation in B. subtilis. However, irreversible Cld inactivation would probably reduce degradation efficiency. As organisms like A. oryzae GR-1 are able to grow with perchlorate as sole electron acceptor nevertheless, probably B. subtilis would be viable as well. Still it could be considered to produce hypochlorite scavengers, which have been shown to increase Cld turnover numbers, like methionine
[10] or guaiacol
[4] in situ to increase degradation efficiency.
Chlorite dismutase (Cld) is a well-characterized enzyme that is present in solution predominantly as a homopentamer, although its enzymatic activity is independent from oligomerization [18]. As suggested by Prof. Dr. Viktor Stein, we investigated the feasibility of obtaining an active monomeric form of this protein. Our goal was to enable the fusion of monomeric Cld with perchlorate reductase (PcrAB), producing a single multifunctional enzyme capable of both reducing perchlorate and immediately detoxifying the resulting chlorite.
This coupling minimizes diffusion delays, improving overall efficiency [22]. While Cld’s enzymatic activity is independent of its oligomeric state, its native pentameric structure poses practical challenges for fusion. Accommodating pentamerization would require additional design constraints such as linker optimization and interface stabilization. A monomeric variant simplifies genetic fusion, improves predictability, and reduces the risk of misfolding or aggregation.
To express our designed constructs, we cloned stratigically mutated sequences into the pQE expression vector, transformed E. coli BL21 cells, and induced expression with IPTG. After lysis, soluble and insoluble fractions were analyzed via SDS-PAGE [23].
After IPTG induction, only the wild-type Cld (QCld) sample shows a visible Cld band in the soluble fraction. No detectable expression was observed for designs 2–4 or the Cld-GFP fusion, indicating unsolubility of these variants.
Insoluble Cld bands are visible for the wild-type (QCld) and design 2 samples (see Figure 14), suggesting that design 2 is expressed but insoluble. Figures 13 and 14 illustrate that, except for design 2, none of the engineered constructs produced detectable amounts of Cld. In design 2, Cld was visible only in the insoluble fraction, suggesting misfolding or structural disruption.
The mutations may have interfered with the native pentameric assembly of Cld but were not sufficient to induce solubility of the monomer. For future work, it would be important to revisit the induction protocol, potentially lowering expression temperature to improve folding. Reducing the number of mutations and focusing on targeted changes could clarify the role of specific residues. Although the outcome did not meet expectations, it provided valuable insight into the complexity of protein engineering and the importance of optimizing both design and experimental conditions.
Our growth curve assay revealed no effect of the pMK4 cld construct in Bacillus subtilis when exposed to 0-8 mM chlorite, compared to the empty vector control.
To evaluate the functionality of our cld expression construct, we aimed to test whether the production of chlorite degrading Cld in Bacillus subtilis would indeed improve tolerance against chlorite. Comparing growth under different chlorite concentrations was expected to reveal whether the enzyme can effectively protect the cells.
Our growth curve assay across 0-8 mM chlorite showed no protective effect of cld, as the growth of Bacillus subtilis carrying pMK4 cld was not significantly higher than that of the empty vector control, as seen in Figures 15 - 23.
Overall, the growth rate of the pMK4 cld strain was never higher than that of the empty vector control, as can be seen in Figure 24. Only for 5 mM chlorite growth rate difference was significant, see Table 4.
| Chlorite concentration | 0 mM | 1 mM | 2 mM | 3 mM | 4 mM | 5 mM | 6 mM | 7 mM | 8 mM |
|---|---|---|---|---|---|---|---|---|---|
| p-value | 0,890 | 0,313 | 0,198 | 0,226 | 0,056 | 0,011 | 0,060 | 0,268 | 0,086 |
Several factors may explain the absence of a growth advantage of our engineered strain.
One possibility is that chlorite dismutase may not have been functionally active under the tested conditions.
Although Cld is known to be highly effective in chlorite degradation
[5
,14], its expression in our construct may have been insufficient. For example, if the chosen promoter was not active in Bacillus subtilis under chosen culturing conditions.
Moreover, as the enzyme is heme-dependent
[18], incomplete heme incorporation or insufficient maturation could, in principle, have led to an inactive protein unable to degrade chlorite. However, this explanation is less likely, since Stefan Hofbauer confirmed that Bacillus subtilis is able to synthesize heme b and thus assemble active holo-chlorite dismutase (see Human Practice)
[24].
On the other hand, Cld enzymes usually fulfill their function in the periplasm [3], while our construct was expressed in the cytosol without an B. subtilis export sequence.
This mislocalisation may have prevented the enzyme from degrading chlorite in the medium. Strong heterologous expression could also have imposed a metabolic burden on the cells, further reducing growth.
Another important consideration is the quality of the cultures themselves.
During the experiment, we observed unexpected growth patterns in the controls, suggesting that contamination or culture impurity cannot be excluded. For example, the pMK4 cld culture may not have been fully homogeneous. Such issues would compromise comparability and may have masked potential protective effects.
Overall, our data indicate that expression of cld in Bacillus subtilis under the current construct and/or assay setup did not improve chlorite tolerance. This outcome did not meet our initial expectations, as we anticipated that expression of chlorite dismutase would provide a growth advantage in the presence of chlorite.
The absence of such an effect is likely explained by a combination of biological factors, such as enzyme inactivity, mislocalisation or cellular burden and technical issues, including possible contamination.
These findings highlight the need for improvement in future experiments and applications. A first step will be to verify cld expression. For example by using a western blot or by fusing the enzyme to GFP, in order to confirm that the promoter is functional and the protein is expressed in Bacillus subtilis. In addition, the cellular localization of Cld should be examined. This can be done by performing a western blot to determine whether it is solubly expressed and if it reaches the intended compartment. Since chlorite dismutase functions naturally in the periplasm, directing the protein to the cell surface may allow it to encounter chlorite directly in the medium, thereby enhancing detoxification efficiency. To further test if heme incorporation is limiting, heme can be supplemented to cultures or lysates and the effect on Cld activity can be measured. Finally, stricter culture handling and quality control will be important, as contamination or heterogeneity between replicates may have masked potential effects.
We aimed to evaluate the perchlorate degrading capabilities of Azospira oryzae GR-1 and Bacillus subtilis 168 using a low-cost organic phase extraction method to quantify perchlorate reduction efficiency.
Starting from 200 ppm perchlorate, A. oryzae wild type (WT) showed no decrease in perchlorate concentration over 7 days of incubation, see Figure 25. Although it is known as a natural perchlorate reducer [25], our results suggest that critical growth parameters, such as trace element composition, ionic ratios, or redox balance were not met, despite the use of degassed media and mineral oil overlays.
In contrast, B. subtilis cultures demonstrated a reduction in perchlorate. After nine days, the strain carrying the empty pMK4 vector reached ~89 ppm perchlorate (starting from 200 ppm). Although B. subtilis lacks a native perchlorate reductase, its nitrate reductase catalyzes perchlorate to chlorite conversion [26] (see Figure 25). For the pMK4_cld vector transformed B. subtilis no statement can be made due to high variance between tested replicates.
To confirm perchlorate conversion, chloride ions were quantified using a Macherey-Nagel Nanocolor® chloride test kit. With the B. subtilis pMK4 strain we could measure an incraese of chloride but given the 1 ppm perchlorate to 0.356 ppm chloride conversion ratio this was not accurately measurable with the kit since the M9PT Media contains more than 1000 ppm chloride ions.
Nevertheless, the trend that B. subtilis degraded perchlorate under our conditions might indicate that it is a more robust chassis than A. oryzae for perchlorate bioremediation.
These findings indicate that B. subtilis, despite lacking a native perchlorate reductase, can partially degrade perchlorate through its endogenous nitrate reductase. With the addition of the cld gene, it has the potential to achieve complete perchlorate degradation while avoiding toxic chlorite accumulation. However, nitrate reductase has a very low perchlorate affinity compared to perchlorate reductase. Thus for complete purification of water from perchlorate, introduction of perchlorate reductase genes into our chassis would still be necessary [3].
Our results demonstrate significant progress toward a biological system for perchlorate degradation, both as proof-of-concept and as a foundation for future applications. We achieved the first successful heterologous expression of perchlorate reductase in E. coli and verified its activity - an important step toward easier, cheaper enzyme characterication. Producing this complex enzyme with an affinity tag in a laboratory workhorse like E. coli removes the need to rely on slow-growing or hard-to-cultivate native perchlorate-reducing organisms, making the enzyme far more accessible for further research and engineering. In parallel, we became the first iGEM team to successfully produce and purify chlorite dismutase in E. coli, and investigated a simple, low-cost activity assay designed to be accessible to other iGEM teams. Together, these advances establish a practical platform that lowers barriers for future studies, enabling both academic researchers and future iGEM teams to explore new applications of perchlorate degradation technology.
We also cloned and characterized chlorite dismutase expression in Bacillus subtilis 168. For the final application, genomic integration of the genes of both, chlorite dismutase and perchlorate reductase, can ensure stable expression.
Beyond molecular work, we created an affordable, open-source Random Positioning Machine (RPM) that enables the study of biology in microgravity and can simulate Martian gravity on Earth. Our validated design provides iGEM teams with a powerful new tool to examine the influence of microgravity on parameters like cellular growth or gene expression. The modular anaerobic bioreactor we built from readily available, low-cost materials enables easy replication and adaptation for different applications.
Looking ahead, we envision our project forming the basis of practical tools for both space and Earth. For Mars missions, our system could be packaged as an “emergency water kit” a lightweight plastic-bag bioreactor combined with pills containing engineered spores and nutrients that only require water to initiate perchlorate detoxification. On Earth, our optimized perchlorate detection assay could be adapted into a simple test kit for farmers to monitor soil and water quality in contaminated regions [28].
Together, these directions bring us closer to building biotechnology that safeguards life not only on Mars, but also here on Earth.
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